Crossed-fields traveling wave tubes

ABSTRACT

A crossed fields traveling wave tube wherein the pole pieces providing the magnetic field are mounted along the delay line, inside the tube, and magnetic windows are formed in the tube envelope for associating the pole pieces with the magnetic circuit of the tube.

United States Patent 72] Inventors Pierre Nicodeme;

Walter Sobotka; Roland Valat, all of Paris, France [211 Appl. No 838,595

[22] Filed July 2, 1969 [45] Patented Aug. 10, I971 [73 I Assignee Thomson-CS! [32] Priority July 16, 1968 [33] France [541 C ROSSED-F [ELDS TRAVELING WAVE TUBES 3 Claims, 3 Drawing Figs.

52 11.5.0! sis/3.5, 31515.35.315/39.71,313/l60 s1 lnt.Cl ..l-l0lj25/34 [501 Field oiSearch 315/35, 3.6, 39.3,5.35,39.71

[56] References Cited UNITED STATES PATENTS 7 3,027,487 3/1962 Dench 1. 315/393 3,346,766 10/1967 Feinstein 315/3971 3,376,466 4/1968 Gerard 315/3971 Primary Examiner--Herman Karl Saalbach Assistant Examiner-Saxfield Chatmon, .lr. AnorneyCushman, Darby & Cushman ABSTRACT: A crossed fields traveling wave tube wherein the pole pieces providing the magnetic field are mounted along the delay line, inside the tube, and magnetic windows are formed in the tube envelope for associating the pole pieces with the magnetic circuit of the tube.

PATENTEU AUBIOIQ?! 3,599,032

' sum 1 BF 2 CROSSED-FIELDS TRAVELING WAVE TUBES The present invention relates to crossed field travelling wave tubes.

In such tubes the beam is propagated between a delay line and an electrode generally called sole, respectively placed at positive and negative potentials in relation to the cathode and a uniform magnetic field is provided in the space where the beam propagates, perpendicularly to the direction of propagation thereof and perpendicularly to the electric field.

Certain difficulties have been so far experienced in assembling the various components of such tubes with the requisite degree of precision.

It is an object of this invention to overcome such difficulties.

According to the invention there is provided a travelling wave tube with crossed electric and magnetic fields, comprising an envelope and within said envelope, a delay line and a sole electrode bounding the space wherein the electron beam is propagated, and pole pieces positioned along said space for providing a magnetic field therein, said envelope comprising along each of said pole pieces a magnetic window for allowing the association of said pole pieces with a magnetic circuit.

For a better understanding of the invention and to show how the same may be carried into effect, reference will be made to the drawing accompanying the ensuing description and in which:

FIG. I is a perspective exploded view of a crossed-field tube in accordance with the invention; and

FIGS. 2 and 3 are schematic sectional views of details of a tube in accordance with the invention.

In all the figures similar reference numbers designate similar elements.

The tube shown in FIG. 1 is built up from three portions (1 (2) and (3). These three portions are assembled one upon the other, in a manner which will be indicated hereinafter.

The portion (1) comprises a base I which can be cut in a piece of metal and has a stepped profile with a central part 1a and two shoulders lb and 1c, resting on a flange 1d. The base 1 carries the delay line 2 of any suitable design. The base 1 and the delay line 2, both being made of metal, are insulated from one another by a layer of glucine, for example, which is not visible in the figure because of the scale on which it is drawn. On the shoulders lb and 1c, the two pole pieces 3 and 4 are assembled by means of respective screws v and v.

Upon the pole pieces 3 and 4, there are fixed distance pieces of insulating material, such as alumina for example, two for each pole piece in the example of FIG. 1, namely the distance pieces 5, 6, 7 and 8. The screws 9, 10, 11 and 12 secure these distance pieces to the pole pieces.

In operation, the electron beam passes through the tube from the left to the right, above the delay line 2 and between the pole pieces 3 and 4. The end 14 of the central portion 1a, where the electron beam emerges, has a curved profile.

In operation, the base is connected to a circulatory fluid cooling system, through connections which have not been shown.

The tube has a coupling for collecting the input signal; the power is picked up at the output by an antenna 13.

The portion (2) of FIG. 1 shows the sole of the tube. It is essentially formed by a rectangular-section body 21 to which two T-shaped clamps 22 and 23 are fixed by the respective screws 24 and 25. The bars of the Tees are perpendicular to the body 21. Each contains two holes I, and 1 or 1 and t disposed symmetrically with respect to the leg of the T t, is not visible.

The body 21 is terminated at its right-hand end in a raised portion 26 shaped to match the portion 14 of FIG. (1) and, at its left-hand end, where the beam enters, is terminated in a wedge 27. A member 28, inclined in relation to the body 21 and attached both to said body and to the T 22 is designed to carry the electron-gun.

The portion (3) of FIG. 1 perspectively illustrates, the cover 30 of the tube, a portion of the cover having been cut away. The cover 30 has a flange 31. On the side faces, 32 and 33 of the cover 30, two windows 34 and 34' ofsoft iron or another suitable ferromagnetic material, are provided.

The cover 30 has a vacuum connection 36 and a cooling connection 37 and 38. 1

The three portions are assembled one above the other in the following manner:

The sole section 20 is offered -up-above the base 1, with the face opposite that carrying the T members 22 and 23, facing the base, the holes t and z being opposite the screws 11 and 9 and holes t and t opposite the screws 12 and 10, respectively. Then, the sole section 20 is lowered until the bar of the T 22 rests on the distance pieces 5 and 7 and the bar of the T 23 rests on the distance pieces 6 and 8. After adjustment of the position of the sole section (the holes 1,, t t t have slightly larger diameters than those of the screws 9, 10, ll, 12) it is locked on the distance pieces by nuts.

After the fitting of the electron-gun, on the support 28, the cover 30 is fitted on the flange 1d, the windows 34 being applied against the pole pieces 3 and 4 respectively.

The cover is welded to the base by a weld extending around the periphery of the flange 1d of the base 1, for example by electron bombardment or any other suitable technique.

The crossed-field tube of the invention offers numerous advantages over the prior art, namely:

The structure is very compact, as may be seen from the foregoing description;

The various elements of the tube can be assembled together and their positions adjusted in relation to one another with great ease in particular in so far as the mutual position of the sole and the delay line is concerned, due in particular to the insulating distance pieces mounted on the pole pieces;

In so far as the manufacture of the cover is concerned, it is a one-piece component which does not have to satisfy any particular accuracy conditions, except that the magnetic windows must be located exactly in front of the pole pieces located inside the tube.

It should be pointed out that even if there is a small clearance between these components once they are assembled, this clearance will be taken up by deformation of the cover while evacuated. FIG. 2 schematically illustrates, in section, the arrangement of the magnetic circuit in relation to the cover and the base, in a tube in accordance with the invention. In this figure, e represents the clearance in question, and A the magnets.

In the tubes in accordance with the invention, it is arranged that the electron collector is in the leakage field of the magnetic circuit in order to be able to exploit this effect to lessen the impact of the electron beam the collector. The collector 39, which is an integral part of the cover but, being inside it, is not visible in the FIG. ll (3), receives the beam after the latter has passed between the two profiled members 14 FIG. I (1) and 26 FIG. ll (2). It has the form shown schematically in FIG. 3.

A uniform magnetic field B is produced by the magnets A, and is directed towards the rear in FIG. 3, normally to the electric field E.

The induction B, which exists over the full length of the pole pieces, such as 3, also extends towards the profiled end 14 of the base 1 and 26 of the sole 20, and towards the collector 39.

Of course the invention is not limited to the embodiments described and shown which has been given solely by way of example. Thus, the example described is concerned with a linear tube in which the beam is propagated along a linear trajectory between a sole and a delay line which are planar and parallel to each other. Obviousiy the invention is equally applicable to circular tubes of the kind produced by turning this structure into a cylinder the axis of which is perpendicular to the direction of propagation of the beam.

We claim:

1. A travelling wave tube with crossed electric and magnetic fields, comprising:

2. A tube as claimed in claim 1, wherein the electron collector is located within the field provided by said pole pieces.

3. A tube as claimed in claim 1 comprising a base member carrying said delay line and said pole pieces, a sole supported by said pole pieces and a cover member welded to said base member and wherein said magnetic windows are formed. 

1. A travelling wave tube with crossed electric and magnetic fields, comprising: a nonmagnetic envelope and within said envelope, pole pieces, a delay line and a sole electrode bounding the space wherein an electron beam is propagated, said pole pieces being positioned along said space, said envelope comprising along each of said pole pieces a magnetic window of magnetically permeable material for magnetically coupling said pole pieces with an external magnetic circuit.
 2. A tube as claimed in claim 1, wherein the electron collector is located within the field provided by said pole pieces.
 3. A tube as claimed in claim 1 comprising a base member carrying said delay line and said pole pieces, a sole supported by said pole pieces and a cover member welded to said base member and wherein said magnetic windows are formed. 